Communication via address modulation

ABSTRACT

Systems and methods are provided for communication via address modulation on an communication channel. A first processing component is configured to produce a plurality of data packets. Each data packet has an associated address from a plurality of available addresses. The system further comprises a plurality of addressable entities, with each of the addressable entities being represented by a proper subset of at least two of the available addresses. A second processing component is configured to apply at least one conditioning process to the series of data packets. The first processing component is configured to select an address for each packet from the subset of available addresses representing the addressable entity associated with the packet as to communicate data between the first processing component and the second processing component.

FIELD OF INVENTION

The present invention relates to a communications system and, moreparticularly, to a communications system utilizing address modulation.

BACKGROUND OF THE INVENTION

The Advanced Television Systems Committee (ATSC) published a DigitalTelevision Standard in 1995 as Document A/53, hereinafter referred tosimply as “A/53” for sake of brevity. A/53 describes vestigial-sidebandamplitude modulation of the radio-frequency carrier wave using aneight-level modulating signal, which type of over-the-air DTVbroadcasting is called “8-VSB”. Efforts have been made to provide formore robust transmission of data over broadcast DTV channels withoutunduly disrupting the operation of so-called “legacy” DTV receiversalready in the field. Robust transmission of data for reception bymobile and hand-held receivers is provided for in a Candidate Standard:ATSC Mobile DTV Standard published in June 2009, referred to hereinaftersimply as “A/153” for sake of brevity, and incorporated herein byreference. A/153 is directed to transmitting ancillary signals in a timedivision multiplexing arrangement with 8-VSB DTV signals, whichancillary signals are designed for reception by mobile receivers and byhand-held receivers. The ancillary data employ internet protocol (IP)transport streams.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, a communicationssystem is provided. A first processing component is configured toproduce a plurality of data packets. Each data packet has an associatedaddress from a plurality of available addresses. The system furthercomprises a plurality of addressable entities, with each of theaddressable entities being represented by a proper subset of at leasttwo of the available addresses. A second processing component isconfigured to apply at least one conditioning process to the series ofdata packets. The first processing component is configured to select anaddress for each packet from the subset of available addressesrepresenting the addressable entity associated with the packet as tocommunicate data between the first processing component and the secondprocessing component.

In accordance with another aspect of the present invention, a method isprovided for establishing a side communication channel between first andsecond entities in a communications system. A first data stream,representing a content of a main communication channel, and a seconddata stream, representing the side channel, are provided at a firstprocessing component. The first data stream is encoded as a series ofpackets, with each packet having an associated addressable entity. Anaddress is selected for each packet from a plurality of addressesassociated with its associated addressable entity as to encode at leastone bit of data from the second data stream. The second data stream isdecoded from the selected addresses at a second processing system. Atleast one data conditioning process is performed on the first datastream according to the decoded second data stream.

In accordance with yet another aspect of the present invention, apost-processing system for a digital television system is configured toprocess a series of data packets according to an address modulated sidechannel generated through selection of an address for each packet from asubset of available addresses representing an addressable destination ofthe packet. A data randomizer is configured to be responsive to theaddress modulated side channel as to determine if a given packet in theseries of data packets contains main service data or handheld/mobiledata, such that packets containing main service data are randomized andpackets containing handheld/mobile data are not randomized. At least oneTrellis coder is configured to perform one of an initialization processand a training process in response to the decoded second data stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomeapparent to one skilled in the art to which the present inventionrelates upon consideration of the following description of the inventionwith reference to the accompanying drawings, wherein:

FIG. 1 illustrates a communications system configured to transmitaddressable packets between a first processing component and a secondprocessing component in accordance with an aspect of the presentinvention;

FIG. 2 illustrates an exemplary system for broadcasting digitaltelevision signals in accordance with an aspect of the presentinvention;

FIG. 3 illustrates a method for establishing a side communicationchannel between first and second entities in a communications system;and

FIG. 4 illustrates a computer system that can be employed to implementall or portions of the systems and methods described herein, such asbased on computer executable instructions running on the computersystem.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 illustrates a communications system 10 configured to transmitaddressable packets between a first processing component 12 and a secondprocessing component 14 in accordance with an aspect of the presentinvention. Data is provided to the first processing component 12 from adata source 16. The first processing component 12 is configured toencapsulate the provided data into packets, with each packet having anaddress associated with an addressable entity. For example, anaddressable entity can include an entity on an IP (Internet Protocol)network or similar arrangement. Alternatively, an addressable entity cancomprise a particular file designation at a destination (e.g., differentaudio and video channels in a real-time video application).

In the illustrated system, each of the addressable entities can berepresented by at least two addressed, such that the first processingcomponent 12 can select among of the at least two addresses for eachpacket without altering the entity to which the packet is addressed. Forexample, one Internet Protocol (IP) address could map to two availableIP addresses for communication over a channel. In accordance with anaspect of the present invention, the first processing component 12 canbe configured to select among the at least two addresses for a givenpacket as to transmit at least one bit of data. Accordingly, the addressselection at the first processing component 12 is used to provide a sidecommunication channel encoded within the addresses of the packet data.

The packet data, along with the encoded side communication channel, arethen transmitted to a second processing component 14. The secondprocessing component 14 is configured to provide at least oneconditioning process to the data to provide conditioned data suitablefor transmission to the addressable entities. For example, in the caseof the plurality of IP addresses used for a side-channel, thisside-channel information could be used for feed-forward networkconfiguration such as enabling and disabling ports on a network switch.For example, the second processing component can provide one or more ofa data randomization, error coding (e.g., Reed-Solomon or Trelliscoding), synchronization, and similar processes.

In accordance with an aspect of the present invention, data from theside communication channel can be decoded at the second processingcomponent 14 and utilized in the at least conditioning process, suchthat the at least one conditioning process is responsive to the sidechannel data. For example, the side channel can identify one or morecharacteristics of the data encapsulated in the packets to allow thesecond processing component 14 to select or configure a dataconditioning process. It will be appreciate that, through modulating theside communication channel into the packet addresses, the portion of thedata channel reserved for overhead can be reduced.

FIG. 2 illustrates an exemplary system 100 for broadcasting digitaltelevision (DTV) signals in accordance with an aspect of the presentinvention. A mobile/handheld (M/H) multiplexing system 102 receives twosets of input streams, one composed of the MPEG transport stream(MPEG-TS) packets of the main-service data and the other composed of M/Hservice data. The M/H service data are encapsulated in packets at apre-processor 110 before transmission, referred to hereinafter as “MHEpackets”. The pre-processing system 110 combines the MPEG-TS packets ofthe main-service data and the MHE packets of the M/H service data withinone stream of transport packets. Then, a post-processing system 130processes the combined stream for transmission as an ATSC, trellis-coded8-VSB signal.

In the illustrated implementation, which is configured to selectivelyutilize the ATSC A/153 protocol, the post-processing system 130 requiresinformation about the content of the combined signal in order to performits functions. For example, various components need data to selectbetween A/53 and A/153 processing on each packet.

A mobile/handheld (M/H) service multiplex stream of data is supplied toa pre-processor 110 for processing and subsequent encapsulation in thepayload fields of transport packets, referred to hereinafter as “MHEpackets”. To this end, the M/H service multiplex stream of data issupplied to an M/H frame encoder 112, which provides Reed-Solomon (RS)coding of data packets. The data packets are further subjected toperiodic cyclic-redundancy-check (CRC) coding to locate byte errors forthe RS coding. Each M/H frame is composed of one or two frames of the RScoding, and the data in each frame of the RS-CRC coding are randomizedindependently from each other and from the data of the main-servicemultiplex.

The M/H frame encoder 112 provides M/H frames to a block processor 114that provides convolutional coding to the M/H frames. A group formatter116 maps the forward error corrected M/H-service data from the blockprocessor 114 into the corresponding M/H blocks of an M/H Group, addingpre-determined training data bytes and data bytes to be used forinitializing the trellis encoder memories, and inserts 3-byte headersfor the MHE packets. The group formatter 116 also inserts placeholderbytes for main-service data and for non-systematic lateral Reed-Solomonparity. In the illustrated implementation, the group formatter 116assembles a succession of 118 consecutive transport stream packets, withsome of these TS packets are composed of the interleaved convolutionalcoding supplied by the block processor 114, some of these transportstream packets being prescribed training signals stored in read-onlymemory and inserted at prescribed intervals within each M/H Group, andothers being generated by a signaling encoder 120.

The output of the group formatter 116 is provided to a packet formatter122. The packet formatter 122 is configured to remove the main servicedata place holders and the RS parity place holders that were inserted bythe group formatter 116 and replace them with an MPEG header having apacket identifier PID. In accordance with an aspect of the presentinvention, the packet formatter 122 can be configured to select a packetidentifier (PID) for each MHE packet as to provide a transmitter controlchannel (TCC) to the post-processing system 130. For example, the postprocessor 130 needs to be provided with the group formatter bitlocations, which, in the illustrated implementation, are a function ofgroup map.

The post-processing system 130 requires, at a minimum, two pieces ofinformation to perform its functions; specifically whether a MPEG-TSpacket contains M/H pre-processed data and the relationship of thatpacket to the start of an M/H slot. In a first mode of operation,referred to herein as the “TCC standard mode,” the relationship to thestart of an M/H slot can be accomplished using known alignment methodssuch as a cadence signal, provided via inversion of appropriatesynchronization and Distributed Transmission Packet (DTxP) methods, suchas those provided in the A/110 standard. In the illustrated system, thetransmitter control channel can carry the remaining information, as wellas other information deemed necessary.

In an M/H system, slots, which contain M/H data, have 118 contiguousMPEG-TS packets that contain M/H pre-processed data followed by 38contiguous legacy or main MPEG-TS. In accordance with an aspect of thepresent invention, one or more private MHE packet PIDs can be definedfor each of a plurality of addressable entities in the system to allowthese 118 contiguous M/H packets to communicate the full M/H slot groupmap. With two MHE packet PIDs, it is possible to communicate thecomplete group map definition, with space remaining to communicateadditional studio-transmitter link (STL) information such as VSB framealignment.

In accordance with an aspect of the present invention, the transmittercontrol channel communicates in TCC packets, where a TCC packet contains156 TCC words. The first TCC word shall be aligned to the first MPEG-TSin an M/H slot, which in-turn is aligned to a VSB frame. TCC packets aretransmitted in every active M/H slot, where as TCC Null Packet shall betransmitted every non M/H slot. The first 118 TCC words in the TCCpacket provide a TCC payload, where the remainder of the words shallcarry the TCC null word. A sequence of at least fifty TCC null words isused at the end of an M/H slot as a delimiter between TCC packets, andcan be used to determine the start of a TCC packet, as to provide VSBframe alignment. The TCC null packet is a TCC packet where each of the156 TCC words is the TCC null word.

Each TCC message word shall be composed of two hits, a first,MH_present, bit that defines whether the packet contains M/H data and asecond, payload bit that carries the TCC payload if the packet containsM/H data. In the illustrated implementation, the private PIDs used tocarry the transmitter control channel are defined by the two leastsignificant bits of the private PID range, and the TCC null word can bedefined by setting both of the bits to zero.

TABLE 1 TCC Payload Structure for Standard No. of Field Bits Formattcc_mode 2 ‘11’ Reserved 1 ‘1’ tcc_protocol_version 5 uimsbfrs_frame_mode 2 bslbf future_mode 3 bslbf Reserved 3 ‘111’subframe_number 3 bslbf slot_number 4 uimsbf Reserved 1 ‘1’mh_gps_seconds 24 uimsbf If (Optional a/110b   reserved 5 ‘00000’  tx_identifier_level 3 uimsbf 12 uimsbf   tx_address 12 uimsbf  } else{    reserved 32 for (i=0, i<27,  } reserved 18 for (i=0, i<23, crc_8 8uimsbf

Mode

Table 1 illustrates the structure of the payload a TCC packet when thesystem 100 is operating in TCC standard mode. A tcc_mode field uses twobits to specify a TCC mode of operation. A first value “11” indicatesthat the TCC standard mode is being used, while a second value “00”indicates the use of a TCC extended mode, which will be discussed indetail below. A tcc_protocol_version field is a five-bit unsignedinteger field representing the version of the structure of the TCC datastructure syntax. The two most-significant bits are the major versionlevel and the least-significant three bits are the minor version level.In practice, a change in the major version level shall indicate anon-backwards-compatible level of change, while a change in the minorversion level, provided the major version level remains the same, shallindicate a backwards-compatible level of change. For a system asdescribed herein, the value of this field is set to ‘11111’, if thesystem utilizes the minor protocol versioning mechanism option.

An rs_frame_mode field identifies the RS Frame mode of the set ofParade(s) sharing identical parade_id, which a given M/H Group belongsto, for the current M/H Frame. A subframe_number field is a three-bitfield that identifies the current M/H subframe, with valid valuesbetween zero and four, inclusive. A slot_number field is a four-bitfield identifying the current M/H slot within the current subframe, withvalid values between 0 and 15, inclusive. A mh_gps_seconds field is atwenty-four bit unsigned integer field that indicates the elapsed time,measured in 100 ns increments, between a 1-second tick of the GPS clockand the first bit of the MPEG-2 packet sync byte in the header of thefirst MPEG-TS packet of the TCC packet. This allows the relationshipbetween the one PPMF and one PPS can be distributed across thestudio-transmitter link. A crc_(—)8 field provides an unsigned eight-bitinteger representing an eight-bit cyclic redundancy check withX₈+X₇+X₆+X₄+X₂+1 as polynomial which is computed over the first 13 bytesof the TCC payload.

In some implementations, such as multiple frequency networks,functionality compatible with the ATSC a/110b standard may be desirable.In this case, three additional fields can be added. Anetwork_identifier_pattern field, consistent with ATSC A/110b, is atwelve-bit unsigned integer field representing the network in which thetransmitter is located that provides the seed value for twelve of thetwenty four bits used to set the symbol sequence of a unique codeassigned to each transmitter. All transmitters within a network use thesame twelve-bit pattern. A tx_address field is a twelve-bit unsignedinteger field that carries the address of the transmitter to which thefollowing fields are relevant and which is used to seed a portion of aRF watermark code sequence generator. A tx_identifier_level provides athree-bit unsigned integer field that indicates to which of eight levels(including off) the RF watermark signal of each transmitter shall beset.

In accordance with an aspect of the present invention, additionalprivate PIDs can be used to increase the effective bandwidth of theprivate communication channel. When the system is operating in thismode, referred to as the TCC extended mode, the communication channelcan provide addition data, such as an ATSC Time transmitter controlpacket. The extended TCC is based on the normal rules and constructs ofthe standard TCC channel, as described previously, except for the use ofan extended TCC word length of three bits, requiring four private PIDsinstead of the standard two. This expands the TCC payload from 106 bitsto 212 bits. In TCC extended mode, a first, MH_present, bit that defineswhether the packet contains M/H data and second and third bits thatcarry the TCC payload if the packet contains M/H data. In theillustrated implementation, the private PIDs used to carry thetransmitter control channel are defined by the three least significantbits of the private PID range, and the TCC null word can be defined bysetting all three of the bits to zero. In extended mode, the end of theM/H slot is indicated by a sequence of at least one hundred consecutivenull words.

TABLE 2 TCC Payload Structure for Extended Syntax Bits Format tcc_mode 2‘00’ Reserved 1 ‘1’ tcc_protocol_version 5 uimsbf rs_frame_mode 2 bslbffuture_mode 3 bslbf Reserved 3 ‘111’ subframe_number 3 bslbf slot_number4 uimsbf Reserved 1 ‘1’ mh_gps_seconds 24 uimsbfnetwork_identifier_pattern 12 uimsbf tx_tier 4 uimsbf tx_data_inhibit 1bslbf tx_update_timing 1 uimsbf for (i=0; i<12; i++) {   trellis_code_state 3 uimsbf   }  Reserved 2 ‘11’synchronization_time_stamp_extension 1 bslbf tx_identifier_level 3uimsbf tx_power 12 uipfmsbf Reserved 1 ‘1’ synchronization_time_stamp 24uimsbf maximum_delay 24 uimsbf tx _address 12 uimsbf tx_time_offset 16tcimsbf Reserved 1 ‘1’ maximum_delay_extension 1 bslbf crc_8 8

Mode

Table 2 illustrates the bit stream syntax for the TCC extended payloadstructure. The syntax of the original DTxP packet was modified for bothsize constraints and to signal in an extended TCC model. In the TCCextended mode, a tx_tier field was added to replace the original OM_typefield and the trellis_code_state field was modified to remove theredundancy constructs in the DTxP packet. The tx_tier field is afour-bit unsigned integer field that defines the addressed tiers insequence proceeding away from the source end of the network, startingwith 00 for the tier closest to the source and incrementing by one foreach successive tier in the cascade.

The tx_group size was changed from sixteen transmitters to onetransmitter, with one transmitter signaled per active MPH slot and up to80 transmitters can be signaled every MPH frame. The tx_group_numberfield was enlarged to support this change. Finally, in an a/110b system,the update rate is determined by the rate of the DTxP packets in theMPEG_TS. In the TCC extended mode, a transmitter could be sent a new‘DTxP’ packet every MPH slot. It may be undesirable to update timing atsuch a rate, and thus a tx_update_timing field was added to allowsignaling to the transmitter when timing should be updated, supported aslower update rate more typical of an a/110b system.

A synchronization_time_stamp field is a twenty-five bit unsigned integerfield that indicates the elapsed time, measured in bit-time increments,between the ATSC Time (AT) tick and the first bit of the MPEG-2 packetsync byte in the header of the first MPEG-TS packet of the TCC packet.Bit-time increments are defined by the period of an a/53 Transport Rate(TR) bit, nominally 51.6 ns. The 25-bit number is the concatenation ofthe synchronization_time_stamp_extension field and thesynchronization_time_stamp field.

A maximum_delay field is a twenty-five bit unsigned integer field thatindicates the time delay setting in the system, measured in bit-timeincrements, between an AT tick and the first bit of the MPEG-2 packetsync byte in the header of the first MPEG-TS packet of the TCC packet.As with the synchronization fields, the bit-time increments is definedby the period of an a/53 Transport, Rate (TR) bit, nominally 51.6 ns.The 25-bit number is the concatenation of maximum_delay_extension andmaximum_delay.

Each of twelve trellis_code_state fields provide 3-bit field carryingone copy of the three bits of the state of a precoder. Atx_update_timing field is a one-bit unsigned integer field that definedwhether a transmitter should use the content of the Extended TCC payloadto adjust emission timing. A ‘1’ instructs the transmitter to adjust thetiming, and a ‘0’ instructs the transmitter to maintain current emissiontiming.

A tx_data_inhibit field is a one-bit field that indicates when thetx_data information should not be encoded into the RF watermark signal.A tx_time_offset field is a sixteen-bit signed integer field thatindicates a time offset, measured in bit-time increments, between thereference time determined using the maximum_delay field and the time ofemission of the individual transmitter to which it is addressed. Asbefore, bit-time increments are defined by the period of an a/53Transport Rate (TR) bit, nominally 51.6 ns. A tx_power field is atwelve-bit unsigned integer plus fraction that indicates the power levelto which the transmitter to which it is addressed should be set. Themost significant eight bits indicate the power in integer dB relative tozero dBm, and the least significant four bits indicate the power infractions of a dB.

In addition to the MHE packets provided at the packet formatter 122,main service data is supplied to the packet multiplexer 126 throughpacket timing and program clock reference (PCR) adjustment circuitry128. The packet timing and PCR adjustment circuitry 126 adjusts thetiming of the main service packets to facilitate the multiplexing of themain service data with the MHE packets. The packet multiplexer 126operates as a time division multiplexer to combine the main servicepackets with the MHE packets. The combined output of the multiplexer,including the address modulated transmitter control signal, is providedto a post-processing system 130 configured to process the main-servicedata by normal 8-VSB encoding and to re-arrange the pre-processedM/H-service data in the combined stream to ensure backward compatibilitywith ATSC 8-VSB.

The combined signal is provided to a data randomizer 132 that suppressesthe sync bytes of the 188-byte TS packets and randomizes the mainservice data but not the encapsulated M/H-service data. In accordancewith an aspect of the present invention, the data randomizer 132 can beresponsive to the transmitter control channel, such that some packetsare randomized while others are not. For example, the data randomizercan determine whether data is M/H service data or main service data aswell as one or more other properties of the packets from the transmittercontrol channel and selectively randomize the data packets.

The output of the data randomizer 132 is provided to asystematic/non-systematic Reed-Solomon (RS) encoder 134. Like the datarandomizer, the Reed-Solomon encoder is configured to be responsive tothe data provided in the address modulated transmitter control channel.Specifically, the Reed-Solomon encoder 134 extracts from the sidechannel the type of data (i.e., main service or M/H), the parity bytelocations within each M/H data packet, and any other relevantinformation. From this information, the systematic/non-systematic RSencoder 134, can either perform the systematic RS coding processprescribed in A/53, appending the twenty bytes of RS parity data to theconclusion of the 187-byte packet, or a non-systematic RS encodingprocess, placing the twenty bytes of RS parity data at a locationdefined within the transmitter control channel, according to theinformation received in the transmitter control channel.

The RS encoded data is provided to a data interleaver 136, configured tosupply byte-interleaved 207-byte RS codewords via a parity replacer 138to a trellis encoder 140. The trellis encoder 140 converts theinterleaved data into symbol units and performs a twelve-phase trelliscoding process. In order for the output data of the trellis encoder 140to include pre-defined known training data, initialization of thememories in the trellis encoder is required.

This initialization can cause the Reed-Solomon parity data calculated bythe systematic/non-systematic RS encoder 134 prior to the trellisinitialization to be erroneous. The RS parity data must be replaced toensure backward compatibility with legacy DTV receivers. Accordingly, anon-systematic Reed-Solomon coder 142 is provided to recalculate the RSparity of the affected M/H packets and provide this parity data to theRS parity replacer 138. The parity replacer substitutes there-calculated RS parity bytes for the original RS parity bytes beforethey are supplied to the modified trellis encoder 140.

In accordance with an aspect of the present invention, each of theTrellis encoder 140, the non-systematic RS encoder 142, and the parityreplacer 144 can be responsive to the transmitter control channel inperforming their respective functions. For example, the transmittercontrol channel can instruct the Trellis coder 140 when it is necessaryto perform the trellis initialization and training processes. Similarly,the non-systematic RS encoder 142 and the parity replacer 144 can beinstructed if it is necessary to perform parity replacement as well asat what locations in the frame the parity replacement is necessary.

The trellis-coded signal is provided to a transmitter system 160 at asynchronization multiplexer 162. The synchronization multiplexer 162receives the trellis-coded data generated by the trellis encoder 140 andat least synchronization signals comprising the data segment sync (DSS)and the data field sync (DFS) signals. The two synchronization signalsare time-division multiplexed with the trellis-coded data and suppliedto a pilot inserter 164. The pilot inserter 164 introduces adirect-component offset into the signal for the purpose of generating apilot carrier wave during subsequent balanced modulation of a suppressedintermediate-frequency (IF) carrier wave.

The signal provided by the pilot inserter 164 is filtered at apre-equalizer filter 166 and provided to an 8-VSB exciter 168. The 8-VSBexciter 168 supplies the suppressed IF carrier wave to a radio frequency(RF) up-converter 170 to be upconverted to a desired broadcastfrequency. The RF up-converter 170 can include a high power amplifierconfigured to amplify the power of the radio frequency (RF) signalbefore transmitting the signal at a broadcast antenna 172.

FIG. 3 illustrates a method 200 for establishing a side communicationchannel between first and second entities in a communications system inaccordance with an aspect of the present invention. At 202, a first datastream, representing a content of a main communication channel, and asecond data stream, representing the side channel, are provided at afirst processing component. It will be appreciated that each of thefirst data stream and the second stream can be generated at the firstprocessing component or generated externally and transmitted to thefirst processing component. In one implementation of the method 200, atleast a portion of the second data stream is derived in response to oneor more characteristics of the first data stream.

At 204, the first data stream is encoded as a series of packets, eachpacket having an associated addressable entity. In accordance with anaspect of the present invention, each addressable entity can have aplurality of associated packet addresses. At 206, an address is selectedfor each packet from a plurality of addresses associated with itsassociated addressable entity as to encode at least one bit of data fromthe second data stream. Essentially, the data from the second datastream are modulated on to the address data via the selection at 206, asto form a second data channel, representing the second data stream,within the series of packets representing the first data stream.

The series of packets is provided to a second processing component at208, and at 210, the second data stream is decoded at the secondprocessing component from the selected addresses. The second processingcomponent can be configured to match each selected address to a word ofdata, and thus recover the contents of the second data stream. At 212,at least one data conditioning process is performed on the first datastream according to the decoded second data stream. In oneimplementation, the second data stream contains data describing one ormore characteristics of the first data stream, and the at least one dataconditioning process can be selected and configured according to thisdata.

FIG. 4 illustrates a computer system 300 that can be employed toimplement systems and methods described herein, such as based oncomputer executable instructions running on the computer system. Thecomputer system 300 can be implemented on one or more general purposenetworked computer systems, embedded computer systems, routers,switches, server devices, client devices, various intermediatedevices/nodes and/or stand alone computer systems. Additionally, thecomputer system 300 can be implemented as part of the computer-aidedengineering (CAE) tool running computer executable instructions toperform a method as described herein.

The computer system 300 includes a processor 302 and a system memory304. Dual microprocessors and other multi-processor architectures canalso be utilized as the processor 302. The processor 302 and systemmemory 304 can be coupled by any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, and alocal bus using any of a variety of bus architectures. The system memory304 includes read only memory (ROM) 308 and random access memory (RAM)310. A basic input/output system (BIOS) can reside in the ROM 308,generally containing the basic routines that help to transferinformation between elements within the computer system 300, such as areset or power-up.

The computer system 300 can include one or more types of long-term datastorage 314, including a hard disk drive, a magnetic disk drive, (e.g.,to read from or write to a removable disk), and an optical disk drive,(e.g., for reading a CD-ROM or DVD disk or to read from or write toother optical media). The long-term data storage can be connected to theprocessor 302 by a drive interface 316. The long-term storage components314 provide nonvolatile storage of data, data structures, andcomputer-executable instructions for the computer system 300. A numberof program modules may also be stored in one or more of the drives aswell as in the RAM 310, including an operating system, one or moreapplication programs, other program modules, and program data.

A user may enter commands and information into the computer system 300through one or more input devices 320, such as a keyboard or a pointingdevice (e.g., a mouse). These and other input devices are oftenconnected to the processor 302 through a device interface 322. Forexample, the input devices can be connected to the system bus by one ormore a parallel port, a serial port or a universal serial bus (USB). Oneor more output device(s) 324, such as a visual display device orprinter, can also be connected to the processor 302 via the deviceinterface 322.

The computer system 300 may operate in a networked environment usinglogical connections (e.g., a local area network (LAN) or wide areanetwork (WAN) to one or more remote computers 330. A given remotecomputer 330 may be a workstation, a computer system, a router, a peerdevice or other common network node, and typically includes many or allof the elements described relative to the computer system 300. Thecomputer system 300 can communicate with the remote computers 330 via anetwork interface 332, such as a wired or wireless network interfacecard or modem. In a networked environment, application programs andprogram data depicted relative to the computer system 300, or portionsthereof, may be stored in memory associated with the remote computers330.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims. The presentlydisclosed embodiments are considered in all respects to be illustrative,and not restrictive. The scope of the invention is indicated by theappended claims, rather than the foregoing description, and all changesthat come within the meaning and range of equivalence thereof areintended to be embraced therein.

1. A communication system comprising: a first processing componentconfigured to produce a plurality of data packets, each data packethaving an associated address from a plurality of available addresses; aplurality of addressable entities, each of the addressable entitiesbeing represented by a proper subset of at least two of the availableaddresses; and a second processing component configured to apply atleast one conditioning process to the series of data packets; whereinthe first processing component is configured to select an address foreach packet from the subset of available addresses representing theaddressable entity associated with the packet as to communicate databetween the first processing component and the second processingcomponent.
 2. The system of claim 1, the first processing componentbeing configured to select a first address for a packet from the subsetof available addresses representing the addressable entity associatedwith the packet when the packet contains a first type of data and asecond address for the packet when the packet contains a second type ofdata.
 3. The system of claim 1, the second processing component beingconfigured to apply a first conditioning process to a given packet whenthe first processing component selects a first address and apply asecond conditioning process to the packet when the first processingcomponent selects a second address.
 4. The system of claim 1, the firstprocessing component comprising a pre-processing system in a digitaltelevision system and the second processing component comprising apost-processing system in the digital television system.
 5. The systemof claim 4, the first processing component being configured to select anaddress for each packet from the subset of available addressesrepresenting the addressable entity associated with the packet as tocommunicate timing information between the first processing componentand the second processing component.
 6. The system of claim 4, thepre-processing system comprising a packet formatter configured to selecta first address for a packet from the subset of available addressesrepresenting the addressable entity if the packet contains M/Hpre-processed data.
 7. The system of claim 4, the post-processing systemcomprising a data randomizer configured to determine from the addressselected at the first processing component, if a given packet in theseries of data packets contains main service data or handheld/mobiledata and at least one other property of the packet, and selectivelyrandomize the plurality of packets according to this determination. 8.The system of claim 4, the post-processing system comprising asystematic/non-systematic Reed-Solomon encoder configured to determinefrom the address selected at the first processing component if a givenpacket in the series of data packets contains main service data orhandheld/mobile data and at least one other property of the packet, andselectively provide one of a systematic Reed-Solomon encoding or anon-systematic Reed-Solomon encoding to a given set of packets accordingto this determination.
 9. A method for establishing a side communicationchannel between first and second entities in a communications systemcomprising: providing a first datastream, representing a content of amain communication channel, and a second data stream, representing theside channel, at a first processing component; encoding the first datastream as a series of packets, each packet having an associatedaddressable entity; selecting an address for each packet from aplurality of addresses associated with its associated addressable entityas to encode at least one bit of data from the second data stream;decoding the second data stream from the selected addresses at a secondprocessing system; and performing at least one data conditioning processon the first data stream according to the decoded second data stream.10. The method of claim 9, wherein the at least one data conditioningprocess comprises Trellis coding and performing the Trellis codingprocess on the first data stream according to the decoded second datastream comprises performing one of a Trellis initialization process anda training process in response to the decoded second data stream. 11.The method of claim 9, wherein performing the at least one dataconditioning process comprises selectively performing a parityreplacement on the first data stream according to the decoded seconddata stream.
 12. The method of claim 9, wherein performing at least onedata conditioning process comprises selectively providing one ofsystematic Reed-Solomon encoding or non-systematic Reed-Solomon encodingaccording to the decoded second data stream.
 13. The method of claim 9,wherein selecting an address for each packet from a plurality ofaddresses associated with its associated addressable entity as to encodeat least one bit of data from the second data stream comprises encodingtiming data within the second data stream.
 14. The method of claim 9,wherein providing a first data stream comprising providing a data streamcomprising MPEG formatted video.
 15. The method of claim 9, the seconddata stream comprising data for performing a cyclic redundancy check onthe first data stream.
 16. The method of claim 9, wherein providing afirst data stream and a second data stream comprises deriving the seconddata stream from the first data stream.
 17. The method of claim 9,further comprising transmitting the first data stream at an associatedtransmitter.
 18. A post-processing system for a digital televisionsystem configured to process a series of data packets according to anaddress modulated side channel generated through selection of an addressfor each packet from a subset of available addresses representing anaddressable destination of the packet, comprising: a data randomizerconfigured to be responsive to the address modulated side channel as todetermine if a given packet in the series of data packets contains mainservice data or handheld/mobile data and at least one other property ofthe packet, such that a first set of packets are randomized and a secondset of packets are not randomized; and at least one Trellis coderconfigured to perform one of an initialization process and a trainingprocess in response to the decoded second data stream.
 19. The system ofclaim 18, the post-processing system comprising asystematic/non-systematic Reed-Solomon encoder configured to determineif a given packet in the series of data packets contains main servicedata or handheld/mobile data and at least one other property of thepacket from the address modulated side channel, and selectively provideone of a systematic Reed-Solomon encoding and a non-systematicReed-Solomon encoding to a given set of packets according to thisdetermination.
 20. The system of claim 18, further comprising a parityreplacement component configured to determine if a given packet in theseries of data packets contains main service data or handheld/mobiledata and at least one other property of the packet from the addressmodulated side channel, and selectively perform a parity replacementaccording to this determination.